1. Technical Field
The present application relates to lighting equipment, and more particularly to a digital dimming circuit.
2. Description of the Related Art
Light emitting diode (LED) is growing in popularity due to decreasing costs and long life compared to incandescent lighting and fluorescent lighting. LED lighting can also be dimmed without impairing the useful life of the LED light source.
Recently, a number of LED lighting apparatuses have been designed to replace the halogen apparatus, as well as other traditional incandescent or fluorescence lighting apparatuses. As in the use of different lighting environment, or in the same lighting environment the light intensity of the light is different, it is needed to adjust the LED light intensity. Therefore, it is needed to adjust the output power of the drive power of the LED lighting apparatuses by dimmers. Usually, there are two ways to dim, one is directly connected to a resistance, and the other is to manually adjust via a potentiometer.
About the way of direct connection of the resistance, it is a most simple and most direct way. However, there are the most problems as the different drive powers of the different manufacturers have on the different output current value during the 1-10 volts. Therefore, when the selected potentiometer is not appropriate the LED lighting apparatuses may have a large dimming dead zone, or it is difficult to be up to the maximum dimming brightness. Moreover, for 1-10V dimming system, it is usually connected a number of drive powers in parallel. As a result, only the potentiometer is almost impossible to play a role of adjustment. Because when multiple power supplies are connected in parallel to the 1-10V dimming system and multiple LED lamps are connected to the power supplies respectively, the brightness of each of the LED lamp is reduced, i.e., below the brightness when only one LED lamp is connected to the dimming system. For another way, it is realized by adjust the voltage value of the voltage divider resistor via a triode with the potentiometer. As above mentioned, the potentiometers are used in these two methods to achieve dimming. However, with the intelligent development, it uses more and more interactive interface and it cannot be resolved only via the potentiometer as it always need to manually operate. Therefore, it began to use the MCU (Microcontroller Unit) to load the desired output voltage into 1-10 V dimming general route.
Therefore, it is necessary to provide a digital dimming circuit which use the MCU to settle out the above art problem.